Maritime traffic corners whales: only 8% of their habitats are safe from deadly ship collisions

The thousands of ships that move from one part of the ocean to another every day are corralling the whales to the point that only 8% of their habitats are safe from maritime traffic. These are the conclusions of a work published this Thursday in the magazine Science by the team of Anna Nisi in which, after crossing data on global maritime traffic and whale habitats, they have found that global maritime transport overlaps with 92% of cetacean habitats.

The global shipping industry has become a worrying source of whale mortality worldwide, with ship strikes contributing to unsustainable mortality rates for several populations, including species on the brink of extinction.

“There are critical risk points in all oceans, except in the Southern Ocean,” explains Nisi to elDiario.es. “Our analysis shows that whales are exposed to an enormous amount of maritime traffic, creating a widespread risk of collisions between whales and ships. At the same time, current protections are limited: less than 7% of the most dangerous areas contain any type of management measure designed to reduce the risk of collision.

A global risk

For this work, Nisi and his team have combined the whale locations (about 435,000 observations for four species with global distribution from hundreds of data sets) with information from the automatic identification system (AIS) of almost 176,000 large vessels to identify critical ship collision points for blue whales, humpbacks, fin whales and sperm whales.

Hotspots exist in all oceans except the Southern Ocean. Less than 7% of the most dangerous areas contain any type of measure to reduce the risk of collision

Anna Nisi
— Researcher at the University of Washington and lead author of the study

“Some particularly notable risk areas include the west coast of North America, several regions along the coasts of South America, the Mediterranean, the Azores, the coast of southern Africa, the northern Indian Ocean, the coastal Australia and the coast of East Asia,” explains Nisi.

In addition to revealing that maritime traffic is shrinking the natural range of cetaceans, the authors demonstrate that only a small effort to expand mitigation measures for ship collisions, such as the implementation of ship speed reduction zones, , would be very effective: reducing this circulation in just 2.6% of the ocean could significantly reduce fatal collisions in all high-risk areas.

“There are some simple and effective interventions that can reduce the risk, including reducing ship speed and changing ship routes to avoid areas important to whales,” says the lead author. “Therefore, our analysis indicates that these measures should be expanded to better protect whales. The good news is that many shipping companies are eager to participate in these types of programs.”

It is estimated that currently more than 100,000 large cargo ships circulate the oceans and by 2050 an increase of 1,200% is expected. “Several lines of evidence indicate that existing records of ship collisions represent the tip of the iceberg of the shipping industry’s current and future damage to marine biodiversity,” the researcher noted. David Sims and his colleagues in a recent analysis article in the journal Nature.

The new “whalers”

Natacha Aguilara marine biologist at the Canary Islands Oceanographic Center (IEO/CSIC) who works on the study of cetaceans, recalls that in some areas of the world it is estimated that mortality due to collisions of large whales far exceeds the legally permitted numbers due to human impacts, and that this mortality is preventing the recovery of many populations even when they are no longer the object of whaling.

“Just as land traffic is regulated in areas where protected species live, such as the lynx, we must do the same in the sea,” says Aguilar. “We must demonstrate that we can avoid absurd whale deaths by increasing the responsibility and organizational capacity of human beings.”

We must demonstrate that we can avoid absurd whale deaths by increasing the responsibility and organizational capacity of human beings

Natacha Aguilar
— Marine biologist at the Canary Islands Oceanographic Center (IEO/CSIC)

“Death due to collision of large cetaceans is a cause recognized as very important and significant in different parts of the planet, coinciding with routes of intense maritime traffic,” he says. Antonio Fernandezprofessor of veterinary pathology at the Las Palmas University (IUSA-ULPGC). However, he points out, there is a bias or information deficit in relation to other causes of whale death. “In most cases, when they appear dead floating or on beaches, adequate necropsies are not performed by specialists (veterinary pathologists) to correctly determine the cause of their death, which is a bias in the conclusion of the results. of this work, although it does not in any way minimize the importance of death due to collisions of these large mammals and its population impact.”

The case of the Canary Islands

Natacha Aguilar emphasizes that one of the mentioned species, the sperm whale, has precisely a hot spot for collisions in Spain. “In the Canary Islands, the abundance of sperm whales has been reduced by half in just a decade, bringing them to the brink of local extinction,” he points out. In his opinion, reducing collisions is a duty to protect marine macrofauna; There is mortality of cetaceans, sharks, turtles and other species. “It requires a combination of training, technological, operational and awareness measures,” he says.

Thanks to the forensic analyzes that Antonio Fernández and his team from the ULPGC carry out, in the Canary Islands the identification of death of cetaceans does exist. “Here we have a collision mortality rate of 1.8 sperm whales per year (in the last 25 years), although in the last two years (2023-2024) only one sperm whale has died due to collision,” he says. “In the Canary Islands some shipping companies are implementing mitigation measures. It is essential to have references of when and where these cetaceans are throughout the year to provide ships with this information.”

In the Canary Islands, some shipping companies are implementing mitigation measures. It is essential to have references of when and where these cetaceans are throughout the year to provide ships with this information.

Antonio Fernandez
— Professor of veterinary pathology at the Las Palmas University (IUSA-ULPGC)

Aguilar recognizes that technological projects are being developed in the Canary Islands to improve the detectability of large cetaceans via thermal detection, with the collaboration of fast shipping companies. “They have also arranged for us to teach collision prevention classes to their bridge crews,” he says. “But this should be mandatory for all shipping companies that transit cetacean habitats, worldwide.” In his opinion, more is needed, such as dynamic measurements of route changes and speed. “Speed ​​kills, but it is also necessary for society to be informed that buying everything Made in China [y alimentar este sistema de tráfico marítimo intenso]kill whales.”